Gastrin, which is produced within the pyloric region of the stomach, is a hormone that has the effect of increasing the acid concentration within the gastric fluid and shifting the pH of the gastric fluid to a strongly acidic state (Schubert M L, Peura D A. Gastroenterology, 134: 1842 to 1860, 2008). In other words, by inhibiting the production of gastrin, the acid concentration within the gastric fluid can be reduced, and the tendency towards a highly acidic pH can be suppressed.
It has been reported that, in the stomachs of rats, there are indications that the production of gastrin is inhibited by the existence of bacteria (Uribe A, et al. Gastroenterology, 107: 1259 to 1269, 1994). Further, the stomachs of humans exist in a substantially-germ-free state, and compared with the stomachs of rodents, the acid concentration of the gastric fluid is higher, and the pH is more strongly acidic (Kabir A M, et al. Gut, 41: 49 to 55, 1997). One example of a bacterium that can reside in the human stomach is Helicobacter pylori, which is a known pathogenic bacterium. It has been reported that when the Helicobacter pylori is eradicated from an infected patient, the acid concentration within the gastric fluid increases, and the incidence rate of reflux esophagitis increases (Labenz J, et al. Gastroenterology, 112: 1442 to 1447, 1997).
Lactobacillus johnsonii No. 1088 (hereinafter abbreviated as “No. 1088”) is a lactic acid bacterium of the genus Lactobacillus that has been developed by the inventors of the present invention, and because this bacterium was isolated from the gastric fluid of humans, it has extremely good acid resistance and is able to exist within the human stomach. Further, the bacterium has a powerful growth-inhibitory effect on pathogenic bacteria (such as Escherichia coli O-157 and Helicobacter pylori), and is an extremely useful bacterial strain even among the various bacteria of the genus Lactobacillus (accession number: NITE BP-278).